O-rings are in common use for many sealing applications. Directional control valves provide one example of their use. Directional control valves direct the flow of pneumatic or hydraulic fluid to and from cylinders, fluid motors, or other actuating units. A directional control valve typically includes a spool axially movable within a cylindrical cavity to open and close various passages in the valve body. The cylindrical cavity includes a number of axially spaced annular grooves with O-rings set into some of them. The valve spool is movable axially back and forth within the cylindrical cavity and through the O-rings.
O-rings are subject to damage and wear and, depending on operating conditions, must be replaced from time to time. Heretofore, this has been a painstaking job requiring forceps or other such tools and fingers to manipulate an O-ring axially into the cylindrical cavity until it seats itself in its annular groove. Some control valves have a number of annular grooves. Some of the grooves are for O-rings, and some are fluid passages. In such a case, the placement of O-rings in their proper grooves is not only tedious and time consuming, but also critical.